acne help

i'm a senior in hs & i have always had very nice skin. All summer my skin was clear but as soon as school started i BROKE OUT like crazy as in both my cheeks are covered in acne. i have been really stressed with school and thinking about college lately but this started literally the week school started and i need to get rid of it. i've tried switching face wash and i put apple cider vinegar on my face to help. i also just stared the shot hoping it would maybe help me out but no luck so far. any suggestions?  
i miss my nice skin :(